sexta-feira, 2 de novembro de 2012

So we have the iPad 4 coming out today, and Apple previously made a claim that the SoC (System-on-Chip) powering it would be twice as fast as the previous generation iPad's A5X SoC. Well, we just got some benchmark results on the iPad 4, and they only seem to prove that indeed, the A6X is at least twice as good as the A5X, and in some benchmarks even more than twice.

CPU first, of course. The A6X features a dual-core CPU based on a custom architecture made by Apple, named Swift, much like in the iPhone 5, except the A6X's CPU is clocked at 1.4GHz, as opposed to 1.3GHz in the A6. The performance of the A6X CPU is ok, and is able to keep up with what the Android competition currently offers, not more, not less.

CPU performance has never been Apple's focus, but in the iPad 4 it's ok, at most. At the very least, it matches (and slightly outperforms) the Galaxy S III, at the same clock speed but with two cores less, but it is still destroyed by Samsung's Exynos 5 Dual, Qualcomm's Snapdragon S4 quad-core, and to some extent NVIDIA's Tegra 3. On a per-core performance perspective, Apple's Swift is very good, although the per-core king of the hill now is the new Exynos 5250.

Before going into the GPU, I'll quickly talk about the memory interface in the A6X. Like in the A5X, the memory interface in the A6X is the widest one ever seen on a mobile device. The A6X features a quad-channel LPDDR2-1066 memory controller, bringing the theoretical memory bandwidth up to an impressive 12.8 GB/s. This is, of course, necessary to power the 2048 x 1536 display in the iPad 4.

And then there's the GPU, the biggest change in the A6X. Apple has always been known for pushing the mobile graphics performance forward, and it has done just that again. The A6X features a stunning PowerVR SGX554MP4 quad-core GPU. The main difference between the 543 used in previous-gen iPads and the 554 is a doubling in ALU count per core. having four cores, this, therefore, means that the 554MP4 has a total of 32 ALUs, as opposed to 16 ALUs in the 543MP4, therefore, at the same clock speed, we get doubled performance since the A5X. If we assume that the clock speed remains unchanged, this results in a revolutionary 64 GFLOPS of peak theoretical performance. Apart from that, we get the same PowerVR goodness Apple has always benefited from; a TBDR (Tile Based Deffered Renderer) with unified shader architecture.

The Offscreen Egypt HD test shows us that the SGX 554MP4 is much more powerful than the Adreno 320, but in the Onscreen test, what puts the iPad 4 behind the Adreno 320-boasting PadFone 2 is the iPad 4's immense resolution.

As we can see, the iPad 4 is at the top in every benchmark, except for the Egypt HD Onscreen test, where the iPad's large resolution limits its performance, but at any rate, the margin between the PadFone 2 and the iPad 4 in the onscreen test is almost insignificant. We can see that, once again, Apple has managed to put itself at the very top of mobile graphics performance, by a very large margin.

All of that power results in a giant die area of 123mm2. It is really very large, considering that it is build with Samsung's 32nm HKMG (High-K Metal Gate) process. The A6X sets a new benchmark for other competitors to reach. Samsung's Exynos 5250, despite being from the same generation as the A6X, has already lost to it. The warning goes to NVIDIA, mainly. The graphics company's upcoming Tegra 4 'Wayne' SoC is rumored to have a quad-core Cortex-A15 CPU (which is double the performance of the already champion Exynos 5250), and a Kepler based GPU that allegedly has 24 cores, and will be built on 28nm process. We can rest assured that a quad-core Cortex-A15 will be more than enough, and 28nm will also bring the Tegra series up to date. A Kepler GPU seems promising, too, but NVIDIA will have to work hard if it wants to beat the new graphics performance (and also memory bandwidth) king of the hill, the Apple A6X.